Find the value of f(20) and of f(140)

Tanya has $42 to spend at the dolphin island store. tshirts sell for $7 each and a pair of sunglases sells for $6.tanya buys 3 tshirts. how many pairs of sunglases can she buys with the amount of money she has left

What is the distance between the points (2 -3) and (-6 4) on the coordinate plane

F(x) = 1/x g(x)=x-4 can you evaluate (g*f)(0) ? why or why not?